“I got a really bad bacterial infection on my tongue,” is how Nichols described it. “My gums got infected, and I got shingles in my ear drum. It felt like I’d gotten hit across the face with a broomstick. I couldn’t close my eye, and my tongue tasted like ... I’d drank battery acid. I was just laying around, screaming in agony.”

And that was just

part

of the tribulations that kept the guitarist from his music and his popular band, the Architects, off the road just after their biggest gig ever.

But tonight, headlining a show at the RecordBar, they’re back. And he’s back mostly.

• •

The Architects have embarked on several large tours, including the entire 2010 Warped Tour. But the biggest by far was last year’s 30-show tour opening up for My Chemical Romance.

To Nichols, 35, it was just one piece of how he was getting his act, that is, his life, together. Last September, he married his sweetheart of eight years, Venus Starr, and he started to clean up his rock-band lifestyle. The band was preparing for its most ambitious album yet.

“These were going to be the salad days,” said Nichols. “We’d just honeymooned in New York — our favorite city. The band was going great.”

The first symptoms arrived a week after they got home.

“My face was really sore and my tongue hurt, like a burn. I just kind of charged through it, no-time-to-bleed style.”

Then he had trouble closing his left eye or drawing on a cigarette, as if a dentist had given him a Novocain shot. A wisdom tooth, he thought, but the doctor in urgent care offered another diagnosis. “He said, ‘You’ve got Bell’s palsy. You need to go to a hospital.’ ”

It means facial paralysis. There’s no real treatment. Most recover completely but some symptoms can be permanent. Eventually, he was put on pain medication and steroids.

“They weren’t doing anything but make me feel miserable and not like myself,” he said. He dropped them.

“One doctor told him, ‘You’re going to have to see a nerve doctor, and you’ll probably be on pain management for the rest of your life,’ ” said Venus Nichols. “I remember thinking, ‘That’s not an option. There has to be something else.’ ”

That turned out to be acupuncture. Fred Weaver at the Tao Academy of Kansas City was recommended.

“Conventional medicine really doesn’t treat Bell’s palsy,” Weaver said. “They wait to see if it will go away. We’ve been effective in treating it with acupuncture and a change in diet.”

By April, Nichols was feeling much better, although he still couldn’t raise his left eyebrow. That, and still feeling “ like I got punched in the face hard about three days ago.”

“I went through a period where I was screaming at the heavens and being pissed,” but then he began to improve.

“My face was getting better, spirits were high. So we are just married, and we decide it’s time to buy a new mattress.”

• • •

Perhaps it was a bad idea to scream at the heavens.

When they borrowed a friend’s truck to pick up the mattress, he told them the brakes were acting up.

Nichols was unfazed: “I’ve driven our (band’s) van all over the country. I grew up on a farm with farm trucks. I’m no stranger to a master cylinder going out.”

So it was the onset of afternoon rush hour when they approached a stop sign east of 39th Street and Southwest Trafficway when “I’m getting nothing at all from the brakes,” Nichols recalled. “I’m pumping and pumping. I looked down to make sure I’m not stepping on the gas.”

That borrowed 1975 Ford Ranger? “It’s a death sled.”

He swerved through oncoming traffic, “threaded the needle” through a barricade and into a parking lot, over the lot and through three fences before the truck came to a stop in a concrete embankment at a 45-degree angle, nose down.

Neither he nor Venus appeared hurt, although he had smacked his head. By that night, he was nauseated and dizzy. A CAT scan and then an MRI revealed a neck fracture.

“I was dangerously close to being paralyzed from the neck down,” he said. He’d have to wear a brace for six to 12 months.

“There was so much going on,” said Venus Nichols, who co-owns the Arizona Trading Company in Westport. “I had my business to take care of. There was no time to dwell on what might have happened. We had to focus on making things better.”

Back to Weaver, who prescribed diet to help mend the fracture: “Small scallops to protect the disc and they’re also anti-inflammatory. And we had him cook crab meat with ginger root, which knits the bones.”

In early July, three months after the accident, the neck brace was shed. Nichols: “Every time I went in for an MRI, the doctor said, ‘This is healing perfectly.’ He seemed shocked.”

It had set back his progress with Bell’s palsy, but he and Venus decided to celebrate with a vacation in New Mexico. A few days before leaving, he came home from his bar job at the Union in Westport and microwaved a plate of food left sitting out.

Definitely, do not

curse the heavens.

• • •

That meal precipitated a digestive storm that only now is subsiding. It required three hospital stays in two states.

Instead of scallops and crab, Nichols was treated to gastro-intestinal “cocktails” and enemas. “The only thing that made me feel better was lying in the shower and letting the hot water hit my guts.”

“He thought he was dying,” said Venus Nichols.

His weight dropped 30 pounds, getting down to 155 pounds.

“He could barely walk,” recalled his mother, Suzanne Nichols, a registered nurse. Despite her training, she said, “This was so stressful. Keenan’s never really been sick before.”

Like most people digging out after an emotional hurricane, he talked of bedrock change: “I’m humility’s servant. I have such a new perspective on things.”

Venus Nichols sees it, too: “It has brought us closer. Something had to happen to get us on a really healthy path of life. Our lives weren’t out of control, but, really, this has changed our lifestyle, for the best.”

On a warm Sunday afternoon, the Architects are holed up in their midtown practice space, an unventilated room deep inside a brick building. Yet even from the sidewalk outside the building, passersby can hear the heavy, beefy noise they are making.

The band was formed in 2004 when the Phillips brothers — Brandon, Zach and Adam — retired their ska/punk band the Gadjits and moved to hard-rock/punk. Nichols became lead guitarist in 2007, replacing Mike Alexander.

His health issues have put the band on an unscheduled hiatus. Two months before Nichols came down with Bell’s palsy, the band had returned from the tour and was riding a wave of enthusiasm.

“Far and away it was the single best tour I have ever been a part of,” said Brandon Phillips. “We have never been so well received by audiences or treated so well by a headliner. A truly outstanding time and a major source of momentum for the band.”

They’ve been recording the new music without him, but he’s now preparing to go into the studio.

They have performed twice since Nichols got sick. Sitting in the reception room of the practice space, the four talk about tonight’s show, the first in eight months, and its significance.

“It feels like a lot is riding on it,” Nichols said. “But I really need it.”

Asked about his stamina, he said, “I am going to will myself some stamina. I want to kick holes in the ceiling, but ... I’m going to listen to my body. I won’t be doing any scissor kicks.”